VOA科学技术2023--Study: Heat Spreading Ocean Currents Could Collapse by Midcentury

Study: Heat Spreading Ocean Currents Could Collapse¹ by Midcentury

A new study has predicted that a system of ocean currents that transports warm water northward² could collapse in the next 70 years.

Climate scientists have warned that such collapse could cause sea level rise in the U.S. and extreme weather in Europe.

The currents spread, or circulate, water in the Atlantic Ocean, the U.S. National Oceanic and Atmospheric³ Administration (NOAA) explains. The currents carry warm water north and cold water south.

Two years ago, the United Nations Intergovernmental Panel on Climate Change said it was unlikely that ocean currents would cause disastrous⁴ conditions in the next 80 years or so.

However, the new study recently published in Nature Communications suggests that the huge ocean current system might collapse sooner than some scientists believe.

Altogether, the currents studied by the scientists are known as the Atlantic meridional overturning circulation, or AMOC. It circulates water throughout the Atlantic Ocean. The circulation is very lengthy⁵, taking an estimated 1,000 years to complete. But NOAA says the circulation has been slowing since the mid-1990s.

The Atlantic current called the Gulf⁶ Stream is part of this huge current system, NOAA says.

Scientists in the United States and Germany have warned that a further slowdown or complete halt to the circulation process could create more extreme weather in the Northern Hemisphere. It could also cause sea-level rise on the U.S. East Coast and drought in southern Africa. But predictions about the possible timing⁷ remain unclear.

In the new study, Danish researchers Peter and Susanne Ditlevsen examined sea surface temperatures in the North Atlantic between 1870 and 2020. Under current conditions, they have suggested the circulation system could collapse as soon as 2025 or as late as 2095.

Their prediction is different from a prediction made by the United Nations' Intergovernmental Panel on Climate Change (IPCC) in 2021. The IPCC said the collapse was not likely to happen before 2100.

Julio Friedmann is chief scientist at New York City-based Carbon Direct, a carbon management company. He said in a statement he thinks the latest study makes clear that "action must be swift and profound" to reduce major climate risks.

Stefan Rahmstorf co-wrote a 2018 study on ocean currents in the Atlantic. He also published his comments about the Danish-led study on the website RealClimate. Rahmstorf noted⁸ that the timing of a collapse of Atlantic Ocean currents remains⁹ "highly uncertain."

He added that he finds the IPCC's estimate conservative. "Increasingly, the evidence points to the risk being far greater than 10 percent during this century," Rahmstorf wrote. He added that the problem is likely to remain "...rather worrying for the next few decades."

Words in This Story

drought – n. a long period of time during which there is very little or no rain

swift – adj. happening or moving quickly

profound – adj. very great or intense

uncertain – adj. not sure about something

decade – n. a period of ten years

1 collapse   

vi.累倒；昏倒；倒塌；塌陷

参考例句：

• The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
• The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做了一次彻底的调查分析。

2 northward   

adv.向北；n.北方的地区

参考例句：

• He pointed his boat northward.他将船驶向北方。
• I would have a chance to head northward quickly.我就很快有机会去北方了。

3 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

4 disastrous   

adj.灾难性的，造成灾害的；极坏的，很糟的

参考例句：

• The heavy rainstorm caused a disastrous flood.暴雨成灾。
• Her investment had disastrous consequences.She lost everything she owned.她的投资结果很惨，血本无归。

5 lengthy   

adj.漫长的，冗长的

参考例句：

• We devoted a lengthy and full discussion to this topic.我们对这个题目进行了长时间的充分讨论。
• The professor wrote a lengthy book on Napoleon.教授写了一部有关拿破仑的巨著。

6 gulf   

n.海湾；深渊，鸿沟；分歧，隔阂

参考例句：

• The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
• There is a gulf between the two cities.这两座城市间有个海湾。

7 timing   

n.时间安排，时间选择

参考例句：

• The timing of the meeting is not convenient.会议的时间安排不合适。
• The timing of our statement is very opportune.我们发表声明选择的时机很恰当。

8 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

9 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。